1. Field of the Invention
This invention relates to low cost, compact optical sensors, wherein the displacement of an optical fiber in response to a force applied thereto provides an accurate indication of a deformation occurring in a monitored region.
2. Description of the Prior Art
In many environments, it is desirable to be able to sense the occurrence of local deformation over wide material areas. Such deformations include, for example, fatigue, vibration, flexing, slippage, torsion, and bending. Applications in which deformation monitoring is especially desirable include: automobile, ship, and aircraft manufacturing; testing structural members; molding forms in the construction industry; building pressure vessels, fabricating composite materials, etc.
However, conventional deformation sensing typically requires the utilization of relatively cumbersome and expensive test equipment. More particularly, many wires and complex (mechanical-to-electrical) converters may be required to provide an accurate indication of deformation. Moreover, the size of such conventional equipment makes the deformation sensor generally unsuitable for permanent fixation to the area to be monitored. Accordingly, it becomes difficult to accurately monitor the test area for any long or continuous period of time. What is more, conventional sensing equipment may be undesirably susceptible to weathering or deterioration when exposed to certain environments for lengthy intervals.
Examples of optical apparatus that include an optical fiber and that may provide an indication of a physical parameter (e.g. a pressure or force signal) can be found in the following U.S. patents:
______________________________________ U.S. Pat. No. Issue Date ______________________________________ 2,922,873 January 26, 1960 3,051,003 August 28, 1962 ______________________________________